1. Field of the Invention
The present invention relates to a document feeder for use in a copying machine or the like and, more particularly, to a document feeder to be rested atop an image reading device having a stationary optical system disposed under a contact glass of a copying machine, and adapted to transport a document original along the upper surface of the contact glass thereby allowing the image reading device to read (or browse) an image of the document original. Such a document feeder may comprise a document original plate for holding thereon a document original, a document original feeding mechanism for feeding the document original onto the contact glass from the document original plate, a document original transporting mechanism for transporting the document original fed by the document original feeding mechanism along the upper surface of the contact glass, a document original discharging mechanism for discharging the document original transported by the document original transporting mechanism, and a document original discharge plate for receiving the document original discharged by the document original discharging mechanism, which may all be provided on the image reading device.
2. Description of Related Art
Some imaging apparatuses, for example, digital copying machines, digital facsimiles and digital image readers employ an image reading device adapted to read an image of a document original being transported along the upper surface of a contact glass by means of a stationary optical system disposed under the contact glass. Since such a browse-type image reading device is adapted to read an image of a document original during transportation of the document original, a driving unit for the optical system can be dispensed with. This allows for size reduction of the contact glass. Further, this provides another merit that the components of the document feeder rested atop the image reading device can be made compact, particularly, for size reduction of a document original transporting section for transporting the document original along the upper surface of the contact glass as well as a document original feeding section and a document original discharging section respectively provided upstream and downstream of the document original transporting section.
The document original transporting section, the document original feeding section, the document original discharging section and the like are mounted one on another on the image reading device for assembling thereof. Therefore, the mounting positions of the respective components must be adjusted on a component-by-component basis. This leads to a difficulty in precise positioning, and requires a time-consuming positioning operation and a troublesome maintenance operation.
It is important to precisely align the optical system disposed below the contact glass with the document feeder disposed above the contact glass in the image reading device. The accuracy of the alignment is a critical factor which decides the degree of integrity of an image to be acquired by the image reading device.